A great deal of cancer research centers on the problem of how to selectively kill cancer cells.
Although there was a great improvement in treating cancerous malignancies in the last decade, many patients with metastatic cancer disease fall chemotherapy and other oncology treatments, becoming resistance to the oncology drugs and will die from cancer. Additional drugs should be developed and used for the treatment of those patients.
Many chemotherapy drugs used in oncology affect cancer cells in different ways and in different cell cycle phases. Biological targeting dugs can affect cancer cells by their effect on epidermal growth factor receptors (EGFRs) as the Tyrosine kinase inhibitors. Other biological targeting drugs affect the vascular endothelial growth factor receptors (VEGFRs) and act as anti angiogenetics.
All drugs used in oncology have many side effects, some of them are life threatening. Grade 3 and 4 toxicities are relatively common and can cause death in cancer patients. Often patients have to stop chemotherapy and other drug treatments because of the severe side effects. This may lead to the progression of the disease. If patients have decreased liver and kidney function tests they cannot be given most of the recent oncology drugs. Most chemotherapy drugs affect the bone marrow leading to neutropenia and/or thrombocytopenia and anemia which makes the continuation of treatment an impossible mission.
Chlorotoxin is a 36-amino acid peptide found in the venom of the deathstalker scorpion (Leiurus quinquestriatus) which blocks small-conductance chloride channels, Chlorotoxin binds preferentially to glioma cells, which has the potential to fundamentally improve intraoperative detection and resection of malignancies [Mandana Veiseh et al., Cancer Res., 2007; 67:6882-6888].
Serotherapy is considered to be the only specific treatment against envomenation by scorpions, i.e., patients stung by scorpions are treated with antivenoms, antibodies such as Immunoglobulin or parts thereof, directed towards neutralization of the active pharmacological sites of the venom [M. Ismail, Toxicon, 1994; 32(9): 1019-1026]. In particular, reduction of adverse reaction has been achieved by deleting the Fc part of the antivenom Immunoglobulin, leaving the F(ab′)2 part of the immunoglobulin for treatment. Free F(ab′)2 may not complex to venom, for example due to the venom already-binding to cellular receptors before the treatment is initiated. However, the antivenom may remove toxins fixed on their receptors [Ghalim N. et al., Am. J. Trop. Med. Hyg., 2000; 62(2): 277-283].
The immunoglobulin fractions IgG, F(ab′)2 and Fab of scorpion and snake Antivenoms do not bind to the receptors. It is well known that antibodies do not have the pharmacological activity of their antigens. The antivenom antibodies and their fractions possess pharmacokinetic characteristics that are significantly different from their respective venoms. For example, the venoms and their toxins) are several fold faster in their distribution into the tissues than any of the immunoglobulin fractions [M. Ismail and M. A. Abd-elsalam, Toxicon 1998; 38(11): 1523-1528]. Therefore, any indication of a toxin being effective against some type of cancer is not an indication of the effectiveness of the toxin antibody or fraction thereof.
A few types of cancer cells are especially vulnerable to selective attack because they depend on specific hormones or because their surfaces have unusual chemical features that can be recognized by antibodies. However, it is estimated that even in the absence of antigen stimulation a human makes at least 1015 different antibody molecules. In general, therefore, progress with the vexing problem of anticancer selectivity has been slow—a matter of trial and error and guesswork as much as rational calculation. [Alberts, Bruce et al., Molecular Biology of the Cell, 3rd Ed., p. 1267, Garland Publishing, Inc., New York & London].
Therefore, there is no known indication of the effectiveness of antivenoms against cancer. In particular, there is no indication of the effectiveness of scorpion antivenoms against cancer.